I really love these things. The bots are an awful lot better behaved in Space Age but they still do stupid things, whereas these simply work as expected every time. But they are pretty powerful. Thus I have been thinking:

A base turret can only repair, it has no roboport functions.

If you insert a construction robot it becomes capable of doing anything the construction robot could do. Rather than strictly an energy cost figure out how long it would take a bot to do the task, this gets applied as a cooldown. Lump all bots together for this purpose--if something would take 3 seconds and there are 30 bots in the tower the cooldown is .1 seconds. If the cooldown builds up too much no new tasks will be initiated until it's dropped enough.

If a tower doesn't have a bot it can obtain one the same as it can a repair pack and then it can do what the bot would do. Logistics bots work the same way. If a tower is completely full of bots it will attempt to send a bot to whatever tower has the highest cooldown, or if there are none such the most recently used tower that has not received a bot since it's last use. If a tower has not been used for a long time this drops to sending out anything beyond one bot.

The result would be that the more bots you put in the network the more effective it becomes, it pretty much puts the bots where they are being used. Throughput equivalent to what roboports do, but without the stupid things bots do.